Spring is here, so are chicks in classrooms

A sure sign of spring is the proliferation of classrooms hatching out chicken or duck eggs. While chicks may be cute and entertaining, they are also high-risk sources of Salmonella and some other infectious microorganisms. Numerous Salmonella outbreaks have been linked to contact with hatchling chicks, and care must be taken if teachers are considering having chicks in classrooms.

Things to consider:

  • Who will be in contact with the chicks? Children under 5 years of age, pregnant women and people with compromised immune systems should not have contact with young chicks. This rules out having chicks in preschool and some kindergarten classes, however not everyone follows those standard recommendations. It's also very hard to know whether there may be immunocompromised kids in the classroom. Unless a teacher/school is sure that there are no high-risk children present, they shouldn't have high risk animals.
  • Where will the chicks be hatched and raised? Is it in a contained area?
  • Is the chick area easily and always supervised to ensure that rules are followed? This is important for both children and chicks, since chicks can easily be injured or killed through improper handling.
  • Are protocols in place regarding safe handling and hygiene?
  • Are the chicks going to be in an area where students eat?
  • Are parents going to be notified in advance?
  • Are there plans for sending the birds to an appropriate home when they're done in the classroom?
  • Are the chicks there for a true educational purpose, or just as a novelty?

Hatching chicks can be done relatively safely in appropriate classrooms, with older children, no high-risk individuals, easy access to hand hygiene stations, appropriate protocols and proper supervision. The problem is, these aren't always (or even often) present, and inadequate thought often goes into bringing chicks into classrooms.

Dead birds around a feeder: What to do?

Like any animal, disease outbreaks can occur in wild birds. Unless they are large outbreaks they often go unnoticed, but smaller outbreaks can sometimes be encountered by homeowners with bird feeders. Because bird feeders are mixing sites for birds, they are also sites of disease transmission and a place where deaths can be identified. In an outbreak, feeders can contribute to the spread of  infection between birds, and potentially be a source of infection for people or pets.

A classic example of this is Salmonella infection in songbirds. Outbreaks occur periodically and are often identified by people with bird feeders who start to find the odd dead bird in their yard. Some birds can be healthy carriers of the Salmonella bacterium (and therefore be a source of infection for others), while other birds may get sick and potentially die from the infection. If you have noted dead birds around a bird feeder, consider the potential for a disease outbreak, particularly salmonellosis.

The risk to people and pets from Salmonella outbreaks in birds is reasonably low, and probably greatest in cats. Most reports of songbird-associated salmonellosis (songbird fever) are in cats, because cats are more likely to catch and eat songbirds. Sick birds are easier to catch, further increasing the likelihood of exposure during an outbreak. Exposure is also possible through scavenging already-dead birds and perhaps from exposure to heavily contaminated surfaces or spilled feed around feeders.

General recommendations during an outbreak of salmonellosis in songbirds include:

  • Keep cats indoors. This is a good idea at any time, but if you have an indoor-outdoor cat, keep it indoors if there might be an outbreak underway.
  • If your pet has been exposed to a sick bird or an area where sick or dead birds have been found, and your pet gets sick, make sure you tell your veterinarian about the birds.
  • Clean the bird feeder and then disinfect it by soaking it in 10% bleach for 30 minutes. Rinse it after the bleach treatment. If the feeder is difficult to properly disinfect (or you don't want to try), get rid of it by double bagging it and putting it in the garbage.
  • When cleaning the feeder, do it outside so that you don't contaminate any household surfaces. When handling the feeder, wear disposable gloves and wash your hands after you remove the gloves.
  • Keep the feeder down for 1-4 weeks. This reduces the concentration of birds in the area and may help reduce mingling of sick and healthy birds.
  • Remove any dead birds by burying them at least two feet deep in a flowerbed (not in a vegetable garden!).  This is not very easy or practical however - alternatively, double bag the bodies and put them in the garbage, avoiding direct contact with the birds and washing your hands afterward.

Zoo flu

The pandemic H1N1 influenza virus continues to circulate, although the hype has certainly died down. During the original 2009 pandemic, there were a few reports of infection of domestic animals, particularly ferrets and cats. This wasn't particularly surprising since we know these species are susceptible to human influenza viruses, and with so many people infected and so many people owning pets, a large number of pets were presumably exposed, and a few got sick.

Three animals from the San Diego Zoo also developed H1N1 influenza in the fall of 2009: a badger, a Bornean binturong (also known as a bearcat, see photo) and a ferret. The badger and binturong had severe pneumonia and had to be euthanized, but the ferret survived. Presumably, these animals were infected by an infected person, probably a caretaker. This report just provides more evidence of the ability of this virus to infect a diverse range of species, and the need to consider both the potential role of various animal species in human influenza transmission and the potential for animal disease from contact with infected people.

Photo: A binturong (Arctictis binturong) at Overloon, NL (photo credit: Tassilo Rau, source: http://en.wikipedia.org)

Anyone seen a cobra?

The Bronx Zoo has closed it's reptile house following the disappearance of an Egyptian cobra. Officials noticed the 20-inch-long snake was missing on Saturday, and they are presumably carrying out a diligent and very careful search.

There's probably no risk to the public (as long as the snake wasn't stolen). It's likely curled up hiding somewhere, not cruising the city looking for trouble. The cold weather also helps since the snake wouldn't be able to survive outside of the enclosure for long, on the off chance it did get out of the building.

There's no explanation as to how it escaped, something that I assume is also being investigated carefully considering the typically strict handling and control measures for venomous snakes.

When not to bring your dog to work

In some situations, bringing a pet to work might be acceptable. In other situations, it's totally inappropriate. A UK dentist learned that the hard way.

Ian Hulme-Ribsy, a dentist, was found guilty of unprofessional and inappropriate conduct for several bad behaviours. One was that he brought his dog to his dental clinic and failed to clean his hands after handling it. That's a pretty blatant breach of basic infection control practices, in the sense of both having an animal in a patient care area (outside of a structured visitation program) and failure to use basic standards of hygiene to reduce the risk of disease transmission. (It's particularly troubling when you consider that as a dentist the man would be putting his unwashed fingers directly in patients' mouths.)  It's pretty remarkable considering how much attention is generally paid to infection control in the dental world.

Also included in his list of bad behaviours was giving patients sedatives in liquid form without measuring. He'd just pour some into a plastic cup. Reckless disregard for dosing of sedatives is probably a bigger concern than the dog issue, but both show poor judgment.

Mr. Hulme-Ribsy didn't lose his license, but must practice with restrictions. "... Hulme-Rigby must work under supervision and take courses in record keeping, infection control and dental practice ethics. He must undergo annual infection control and record keeping audits, and is banned from administering benzodiazepine drugs, or any other sedatives. Hulme-Rigby’s case will then be reviewed to decide if he is fit to practise without restrictions."

I have MRSA...should my pet be tested?

I get this question a lot, from both pet owners and veterinarians. Typically, my answer is "no."

Why not?

  • The two big questions I always ask are "why do you want to know and what would you do with the results?"

Sometimes people want to know their pet's MRSA status to see if the pet was the source of their infection.

  • However, MRSA in pets is typically associated with MRSA in humans, i.e. if a pet is carrying MRSA, it probably got it from the owner or another close contact. Finding MRSA in a pet after someone is diagnosed with an MRSA infection doesn't mean the pet was the source. More likely, the person got MRSA somewhere else and passed it on to their pet.

Sometimes, people want to know if their pet is at risk of an infection.

  • Carrying MRSA presumably increases the risk of an MRSA infection, but likely only in animals already at risk of an infection because of underlying disease or other risk factors such as surgery. The risk to the average pet from short-term MRSA colonization is probably limited. Also, if the pet was identified as a carrier, we wouldn't be doing anything to eliminate carriage, since we have no idea if decolonization therapy is effective in animals, and it doesn't seem to be needed (because dogs and cats almost always get rid of it on their own). Therefore, it's hard to justify screening for this reason. If the animal was getting ready to undergo surgery, then that might change my answer.

For me, it's also very important to consider what you'd do with the results of any test. In general, in a household where a person has an MRSA infection:

If the pet tests negative, I'd say that it doesn't 100% guarantee that the pet is truly negative, since no screening test is absolutely 100% sensitive. Also, the test only tells you the status of the pet at the time of sampling. It could have picked up MRSA five minutes after the swabs were taken. So, a negative result means the animal is probably negative. Since it's not absolutely negative and since the pet would be at risk of picking up MRSA from the infected person after it was tested, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose) to reduce the chance of the pet becoming colonized and to reduce the risk of MRSA transmission from pet to person if the pet was actually a carrier.

If the pet tests positive, I'd say that we certainly couldn't say the pet was the source of infection. More likely, it got it from the person with the infection. Since we know that MRSA carriage in dogs and cats is almost always transient, and that they will almost always get rid of it on their own if re-exposure is prevented, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose).

Since my response to either result would essentially be the same, why test?

Efforts are better spent on good household hygiene practices and restricting contact with high risk sites. On both pets and people, this would include the nose, as well as any sites that are infected or sites that are prone to infection (e.g. skin lesions). That's going to be much more worthwhile and rewarding than testing the pet.

Radiation fallout risk for pets?

This isn't an infectious disease topic but I've had a few questions about it nonetheless, so I thought it would be worth making some comments here.

With nuclear meltdown concerns in Japan, some pet owners (particularly on the west coast of the US) are flocking to veterinarians looking for potassium iodide pills for their pets. Potassium iodide is given to people (and I guess it could be given to pets) who have been exposed to radiation or who are at high risk of exposure, as a way to reduce the risk of thyroid cancer. 

For pets in North America, and other regions far away from Japan, the risk of radiation exposure from the damaged nuclear power plants appears to be basically non-existent. There's no evidence that, even with a major meltdown, clinically relevant levels of radiation would reach populated areas in North America or beyond.

  • Even if something unexpected happened, there are intensive monitoring efforts underway downwind (i.e. east) of Japan to detect any spike in radiation levels. There's no need to take potassium iodide weeks in advance - at-risk individuals only need it at the time of exposure.
  • Also consider that if potassium iodide treatment is indicated in pets, it's also needed in people in the same area. Given the available supplies, it'd be hard to justify treating pets if there's not a full supply for all the people who might need it.
  • Potassium iodide isn't a benign drug. Overdosing can cause adverse effects, and we don't have good information about appropriate doses for pets. If it was clearly needed, it would be reasonable to make an educated guess from human doses, but with no indication of need, it makes no sense to take the chance.
  • Compared to humans, pets are probably at much lower risk of adverse effects from radiation exposure, because pets have much shorter lifespans, but the effects of radiation exposure tend to cause disease over very long periods of time.

What about pets in Japan? That's a different story, since there is greater potential for risk of exposure now and perhaps through food and water in the future. Still, broad use of potassium iodide isn't being recommended in Japan in humans and there's no reason to treat pets any differently. If there are regions where treatment of people is recommended and where there are adequate supplies, treatment of pets may be a good idea.

Kinkajou owners beware

Kinkajous are strange little mammals from the Procyonidae family - the same family to which raccoons belong. Kinkajous are native to Central and South America and are occasionally kept as pets, but they don't make great pets because they are strictly nocturnal, can be cranky when woken during the day, and can sometimes be aggressive. Regardless, there is a niche pet trade, particularly in the US.

A recent report in Morbidity and Mortality Weekly Report describes detection of Baylisascaris procyonis (the raccoon roundworm) in pet kinkajous in the US, including:

  • A 10-week-old kinkajou in Tennessee in which Baylisascaris procyonis was found during a routine fecal examination.
  • Detection of Baylisascaris eggs from soil samples under the cages of a kinkajou breeder in Florida (the breeder from which the Tennessee animal was obtained).
  • An unrelated case (11 years earlier) in which adult Baylisascaris worms were found in the intestinal tract of two adult kinkajous that died of other causes.

No human infections (i.e. cases of larval migrans) were linked to infected kinkiajous.

Baylisascaris is a parasite that's extremely common in raccoons, rare (but concerning and sometimes over-hyped) in dogs, and an extremely rare cause of disease in people. While rare in humans, it still gets a lot of attention because when disease does occur, it can cause serious neurological damage, typically in children. The damage is caused by migration of parasite larvae through the body, and through the brain. This can occur after someone swallows infective parasite eggs, which then hatch in the intestinal tract and then embark on their journey through the body.

It's unclear whether Baylisascaris is a common problem in kinkajous (like it is in raccoons) or a rare finding (like it is in dogs), since this report only describes the parasite in a small number of animals, and no larger studies of intestinal parasites in kinkajous have been reported. It would be useful to know whether kinkajous are true reservoirs of this parasite (and therefore whether we should consider all kinkajous to be carriers) or whether infection is just an unusual finding.

Overall, the public health risk is likely limited.

  • There aren't that many pet kinkajous around, as far as I know.
  • While Baylisascaris is nothing to dismiss, to get infected, a person still has to eat infective eggs from feces. The likelihood of transmission from a pet to a person is therefore low if good basic hygiene measures are used.
  • The parasite eggs are not immediately infectious. They have to sit around in the environment before they are infectious, usually for 2-4 weeks. Therefore, prompt removal of feces and careful attention to basic practices like hand hygiene should greatly reduce the risk of transmission.
  • Routine testing and deworming of pet kinkajous should reduce the risk even further.

What does this mean for pet kinkajou owners? Not a lot beyond what would normally be recommended. Pet kinkajous should have good veterinary care and regular fecal examinations. Regular deworming should be discussed with the attending veterinarian, and good hygiene practices should be used to avoid contact with feces, especially old feces.

Photo credit: Robrrb at en.wikipedia

Psittacosis outbreak from a bird fair

A paper in Epidemiology and Infection (Belchior et al 2011) describes an outbreak of psittacosis (Chlamydophila psittaci infection) in people who attended a bird fair in western France in 2008.

The investigation started off with the identification of the bird-associated disease in three people at a local hospital. All three were hospitalized with respiratory disease, and all had attended the bird fair.

  • A critical step in diagnosis of psittacosis and recognition of outbreaks is knowing about bird contact. If bird contact isn't questioned, psittacosis is unlikely to be considered. Too often, physicians don't inquire about animal contact, which limits their ability to detect zoonotic diseases. In this case, a survey on psittacosis was underway, which may have helped.

This finding led to an investigation of the fair to determine what happened and make sure there were no other unidentified cases.

The fair lasted one day, and had 83 exhibitors, 1500 birds and around 600 visitors. The investigators ultimately identified two confirmed cases of psittacosis in people who attended the fair, along with two probable and 44 possible cases. (Possible cases were people who developed respiratory disease and were exposed at the event, but did not necessarily have any diagnostic testing done to confirm the cause).

The reported disease characteristics were pretty typical:

  • Fever in 96%
  • Pneumonia and cough in 63%
  • 98% visited a doctor
  • 23% were hospitalized
  • No one died (psittacosis can be fatal, but is quite treatable if identified in a reasonable time)

Thirty-eight percent (38%) of exhibitors and organizers got sick. That's a very high attack rate for people casually interacting with a group of (presumably) healthy birds. Poor ventilation may have played a role. The fair was held inside, windows were closed and there was no mechanical ventilation. This might have helped the bacterium build up in the air in the building and result in wider, heavier exposure.

The source of infection wasn't determined. They were only able to obtain samples from birds from six of the 83 exhibitors, and all 64 tested birds were negative. Chlamydophila psittaci can be shed by healthy birds, and identification of the source isn't always easy.

It's not guaranteed that everyone who got sick after the fair had psittacosis. You can't rule out the possibility that there were only a couple people with psittacosis and a large number with the flu or another disease, but the incidence of disease, type of disease and timing of disease are all quite suggestive.

How do we prevent outbreaks like this in the future? It's tough to prevent them completely, because you can't tell that a bird is shedding the bug just by looking at it, and testing every bird before a show is  impractical. Risks can probably be reduced by ensuring proper ventilation, limiting crowding of areas, limiting unnecessary direct contact between birds and people, and improving general hygiene practices.

Thanks to Dr. Doug Powell of BarfBlog for sending the article.

More information about psittacosis is available in our archives.

Rabies update

ProMedMail tends to publish a monthly rabies report. While a lot of it involves the same basic issues, there are sometimes a few more interesting stories:

Rabies in a donkey in Georgia

  • Like all mammals, donkeys are susceptible to rabies virus but infections are not particularly common. Raccoon rabies has also be identified in the area, and a bite from a raccoon may have been the source.

Bite from a rabid kitten in Pennsylvania

  • A York County woman was bitten by a kitten that ran into her house when the door was opened for someone else. The kitten bit her when she grabbed it to throw it (hopefully not violently) back outside... an understandable reaction but not what you want to do in a case like this. You need to know whether a wild animal that bites is rabid, and if it gets away, you can't test it. You need to get away from it but keep it contained until someone can come get it. The other problem with people getting rid of the animal is that they might not recognize the risk of rabies. In this case, the kitten was hit by a car after being removed from the house, which allowed for it to be tested.

Yet another report of a dog being exposed to rabies through contact with wildlife, then being euthanized because it was not properly vaccinated.

  • An unvaccinated animal that has been exposed to a rabid animal has to be euthanized or undergo a strict six-month quarantine. A vaccinated animal only needs a 45-day observation at home.

Rabid bobcat attack in Florida

  • Encountering a manic bobcat isn't something I'd like to do, and a LaCrosse, Florida woman spent nine days in hospital after being attacked by one. The 25-pound cat was trying to get the family's cat, then lunged at the woman when she came outside the house, aiming for her neck. Her husband then shot it. They knew that the bobcat needed to be examined, and took the rather unusual approach of bringing it to the hospital emergency room with them (I'd love to have seen that). I don't imagine hospital personnel did anything, but Florida Fish and Wildlife Conservation Commission personnel came and got it, and later confirmed that it was rabid. (Image: Lynx rufus, US Fish & Wildlife Service)

Murray Valley encephalitis suspected in Aussie man and horses

Yesterday, I wrote an equIDblog post about an outbreak of unexplained neurological disease in horses in the Murray River region of Australia.  Today, a ProMed report indicates that Murray Valley encephalitis is now being considered as a possible cause of death in a man from the area.

Murray Valley encephalitis (MVE) is one of the possible causes of the equine neurological disease outbreak, and it's quite likely that if it caused disease in one species in the region, it did the same to another. This rare mosquito-borne disease hasn't been seen in decades in the region, but it's possible that high mosquito numbers following heavy rainfall and flooding have increased the risk of transmission.

While this virus poses a risk to both humans and horses, humans and horses pose no risk to each other.  Both acquire the disease the same way - from mosquitoes - and neither can pass it on to the other.  This is also true of other insect-borne viruses such as West Nile virus and Eastern Equine Encephalitis (EEE) virus.

This is a good example of why human and animal disease surveillance need to be linked, and why governments need to put resources into testing of animals beyond food animals. Rapidly identifying a disease in horses or other animal species can help determine whether there is any risk to humans, and hopefully lead to preventive measures being taken earlier.

Prevention of this disease is focused predominantly on mosquito avoidance. It's impossible to completely prevent mosquito exposure, but some basic practices can help reduce the risk.  Click here for some practical tips on protecting yourself and your horses from mosquitoes.

Image: Location of the Murray River in Australia (click for source)

This Worms & Germs blog entry was originally posted on equIDblog on 13-Mar-11.

Pet raccoon attackes baby, owners in denial

Raccoons are fascinating critters but they don't make good pets. Their curiosity makes them quite disruptive and damaging, and they have seriously injured people (particularly infants). They are also rabies vectors, and in many regions raccoon ownership (along with other wildlife species) is illegal (or only legal with a license). Despite all this, some people continue to keep raccoons as pets, and injuries continue to happen. Unfortunately, it's often not the owners that suffer the consequences, but children.

A one-week-old Griggville, Illinois baby is in hospital after being attacked by her grandparents' pet raccoon. The baby was in a room with the raccoon (not a good idea to start with), when the raccoon starting biting and scratching the baby's face and head. The raccoon's owner thinks the raccoon wasn't being vicious, just curious and trying to get a ribbon off of the baby.

"Rampy was trying to get the bow off the baby's head and it's got long claws and he was scratching up the head trying to get the bow off," said the owner.

Regardless, the fact that it caused severe injury indicates it's a hazard. (Wounds caused by accidents heal at the same rates as those caused my malice.)

Euthanasia of the raccoon was requested to test it for rabies. The owner countered that it had been vaccinated against rabies and dewormed (which raises the question of what veterinarian did this. I'd consider vaccinating and deworming an illegal pet unethical at best).  Further, rabies vaccination does not guarantee that the raccoon isn't rabid. A judge eventually ordered the raccoon to be euthanized.

You'd think the raccoon's owners would be aghast at the attack.  While I can see how they'd be attached to their pet, typically concern over a grandchild takes precedence. Not here, however, as the owners fought the euthanasia order and are railing against local authorities for having the raccoon euthanized after a potentially life-threatening attack. Even the infant's father is taken back by their attitude, stating "If it was somebody's dog that bit a kid, they'd be held accountable. These people should be held accountable for [the raccoon]."

(click image for source)

Another pet treat recall

Jones Natural Chews Company has recalled 2705 boxes of pig ear treats because of a "potential" for contamination with Salmonella. The recall was the result of a routine sampling program by the Washington State Department of Agriculture which revealed that the finished products contained the bacteria.

This shouldn't come as a surprise. Salmonella contamination of raw animal-based pet treats is nothing new, and contaminated treats have been implicated in outbreaks of human salmonellosis. There is a risk to pets as well, since Salmonella can cause disease ranging from mild to fatal. Typically, dogs that eat a little Salmonella don't get sick, but they may under the right circumstances, and even dogs that appear healthy can potentially infect people they are around. Handling the treats is also a risk to people, especially the very young, very old, pregnant women and people with compromised immune systems. Households with any individuals from these groups should avoid having any raw animal-based treats around (unless irradiated).  Anyone having contact with treats (whether they're in a high-risk group or not) should wash their hands afterwards.

More information about the recall can be found here.

Beware of the "Rango" effect

When a particular animal species or breed gets a lot of attention, such as through a popular movie or TV show, there's sometimes a major increase in people wanting one as a pet. The proliferation of Dalmatians after 101 Dalmatians, and people buying Jack Russell terriers in response to Eddie from Frasier are only two examples. Sometimes the trend is fine, but it can result in problems when people get breeds or species that really aren't right for them (this was a big problem with the Dalmatians), and with puppy mills pumping out large numbers of poor quality animals to meet the demand. The problems can be even worse when an exotic species is involved.

Concern has been expressed about the potential for this to occur following the success of the animated movie Rango. The movie features a chameleon, a fascinating reptile but also one that is not that easy to properly maintain in captivity and, like all reptiles, carries a risk of Salmonella transmission to household members. 

PETA and some other groups have expressed concern about a PetSmart promotion whereby people can get a $10 discount on reptiles if they bring in a Rango movie ticket stubs. 

Any increase in demand for chameleons resulting from this promotion will be trouble, because:

  • Odds are most of the animals will not do well if purchased on a whim by someone who isn't adequately prepared to take care of them.
  • Smuggling or legal importation of wild-caught chameleons will probably increase, with the associated very high death rates during the collection and shipping process.
  • Chameleons may end up in households where reptiles are not appropriate, such as those with kids under five years of age, elderly individuals, pregnant women or people with compromised immune systems.

Hopefully the concerns are unfounded, but anyone considering purchasing a chameleon needs to carefully research the care requirements, be aware of the risk of disease transmission in the household, and should look for ethically sourced (i.e. captive bred and properly raised) animals.

Elephant-human transmission of tuberculosis

You can probably tell from various posts that I'm a fan of the CDC's journal Emerging Infectious DiseasesIt's a great journal containing interesting infectious disease reports about people and animals (it's free too, which is a nice bonus). In addition to the ferret infection I wrote about, the last edition also has a very interesting report about tuberculosis (TB) in people associated with an elephant sanctuary.

Tuberculosis is a big problem in elephants. It is relatively common in captive elephants in North America (2-12% are thought to be infected), and it It can be a tricky infection to diagnose, so it's very hard to know who's infected an who isn't.

Beyond being a problem for the elephants (because infection can be fatal), elephants with TB pose a risk to people, and there have been reports of human infections associated with elephant contact. Close and prolonged contact is most often associated with transmission of TB from elephants to people, but this recent report shows that indirect transmission may also be a concern.

The report in question deals with an elephant sanctuary in Tennessee. Problems were identified in July 2009 when routine TB skin testing of some workers at the facility indicated exposure to TB. Further investigation revealed that a quarantined elephant had tested positive in December of 2008. The elephant was diagnosed by culture of a trunk wash - to do this, the elephant is trained to suck water into its trunk and then "exhale" it into a plastic bag. The sample is then cultured for Mycobacterium tuberculosis. Animals with positive trunk washes are considered infectious, just like people with positive sputum (spit) cultures.

The TB history at this facility goes back further. In 2004, they took in two elephants that were known to be infected with TB. They were handled as per USDA Guidelines for the Control of Tuberculosis in Elephants (yes, such a document exists). One died of TB and the other was later released from isolation after treatment, according to the guidelines. In 2006, they took in eight more elephants from the same facility. All were considered high-risk for TB and were tested annually. All samples between 2006 and 2009 were negative, except for that one December 2008 sample. There's concern that since the elephants tested negative, people might have become lax with infection control practices. It's a problem beyond elephant facilities, where compliance slips over time since people may not see the need to continue to do what's required. 

After being notified of the the 2009 human TB test results, Public Health personnel launched an investigation. They eventually determined that 9/46 people whom they were able to contact had positive TB skin tests during the 2006-2009 period, despite having negative tests before then (confirming that they were truly exposed during this period). The strange thing was that it wasn't only the people with prolonged, close contact who were infected. People who worked in the quarantined area in 2009 were significantly more likely to be positive, but of the 13 people that worked in the quarantine area, only one had close contact with any elephant. Furthermore, three of the people who were infected were administrators.

This is where is gets interesting. Normal cleaning practices included the use of high-pressure washing to clean the barn. We know that this increases the risk of spreading bacteria in the air over long distances, and it's generally frowned upon from an infection control standpoint. People in the quarantine area wore respirators to reduce the risk. However, the administrative area was attached to the quarantine area and investigators subsequently determined that there was airflow from the quarantine area into the administrative area. So, when people were cleaning the quarantine area with high pressure washing, they were creating infectious aerosols that spread into the administrative building. That presumably accounted for infection of the people who had no contact with elephants. Furthermore, one of the investigators was also exposed during time spent in the administrative area before the risk was identified.

This highlights a few issues:

  • Infectious diseases continue to surprise us. We may know what they tend to do, but new transmission patterns and new concerns can develop.
  • Power washing can contribute to the spread of infectious diseases. This is a concern in many types of facilities.
  • Infection control compliance needs to be maintained over time, even if it seems like the risks have dropped.
  • Captive elephants continue to pose a risk to people around them, and careful precautions are needed to reduce the risk of exposure to TB.

(click photo for source)

Wierd Mycobacterium infection in a ferret

A letter in Emerging Infectious Diseases (Ludwig et al 2011) describes an uncommon Mycobacterium infection in a pet ferret, with potential human health concerns.

The three-year-old ferret from Germany was taken to a veterinarian with a five-month history of coughing, recent weight loss, vomiting and mild diarrhea. A chest radiograph was taken and "nodular densities" were found in the lungs (these would show up as white spots on the radiograph). This type of finding is usually an indication of something bad going on in the lungs, such as tumours or granulomas. Because of the poor prognosis, the ferret was euthanized. At necropsy, the lung nodules were confirmed, and there were some other abnormalities such as and enlarged spleen and a lot of enlarged lymph nodes. Using a combination of culture and molecular tests, Mycobacterium celatum infection was identified as the cause.

Mycobacteria are a diverse group of microorganisms, whose most notable member is M. tuberculosis, the cause of (not surprisingly) tuberculosis (TB) in humans. Mycobacterium celatum belongs a large group classified as 'non-tubercular' Mycobacterium species.

Mycobacterium celatum is rather uncommon, being first diagnosed in a person with AIDS in 1993, and only being reported sporadically in people since then. Most human infections have occurred in people with compromised immune systems, but there are some reports of people with apparently normal immune systems becoming infected. There is also one previous report of an infection in a ferret. There is no evidence that the ferret reported here had a compromised immune system, so the reason for the infection is not apparent. The source of infection is also unknown. Since there were granulomas throughout the lungs, it suggests that the ferret inhaled the organism, but that can't be proven and there are no clues even suggesting a possible source.

An interesting aspect of this report is the question about whether the ferret's owner may also have been infected. It's perhaps a bit of a stretch, but there was a suggestion that the owner may have been infected as well because he/she reported a chronic cough. Testing was performed and no Mycobacterium (of any species) was detected, but the person was treated with antibiotics prior to being tested so a false-negative culture is possible. The likelihood that the person was truly infected is probably quite low, but it can't be dismissed.

Ferret owners shouldn't be too worried about M. celatum. This is an example of one of many possible rare infections that can be encountered. Similarly, this report doesn't mean that ferrets should be considered at higher risk for causing human infections. Every animal poses some degree of risk to people, and ferrets are actually pretty low-risk overall. Mycobacterial infections aren't something to be too concerned about, but, as suggested in this report, the general concept of considering human disease when something is diagnosed in a pet is excellent and too often overlooked.

(Photo credit: Luke Rutherford)

H1N1 flu outbreak in ferret shelter

We've known for a while that cats and ferrets are susceptible to many human influenza viruses, something that was again demonstrated last year through sporadic (and often fatal) reports of H1N1 influenza in both species. Since H1N1 is still in circulation in the human population, there's still a risk of exposure of cats and ferrets, as was seen in an outbreak at a ferret shelter in Kentucky that began last month.

Over a few weeks, starting in early February, all 17 ferrets at the Ferret Villa Shelter in Erlanger, KY, developed influenza. As expected, coughing, sneezing, fever and lethargy were the first signs of disease, with more severe respiratory disease developing in some. One ferret died, and H1N1 was diagnosed through post mortem testing. Presumably, all of the other sick ferrets had influenza as well. Fortunately, the other 16 ferrets survived with supportive care and should presumably suffer no long-term effects.

There's been no mention of the source of the virus, but it almost certainly came from an infected person. Given the susceptibility of ferrets to influenza and the potential for severe illness, ferret owners should be aware of the risk and restrict contact between their ferrets and anyone with flu-like disease. Ferret shelters or breeders, with larger numbers of ferrets, should take extra precautions.

The risk of transmission from ferrets to people isn't known, but it's logical to assume that there is some degree of risk. An infected ferret could quite plausibly shed enough virus to infect a person under the right circumstances. However, since influenza in a pet ferret most likely came from its owner, and most ferrets don't meet many people outside of their households, the risk to other people in most households is probably limited - most people would probably be exposed via the person who was originally sick before they had a chance to get it from the ferret.

(Photo credit: Luke Rutherford)

Do you wash your hands at a petting zoo?

Petting zoos can be great events (I've said it before and I'll say it again!). I end up visiting many with my kids every year.  Despite the fact that a few petting-zoo-associated disease outbreaks also occur every year, and despite the fact that I deal with infectious diseases every day, I still don't get too concerned about the risk to my family.

Why not?

The main reason is that I can control one of the most important disease prevention measures: making sure my family washes their hands after being in the petting zoo (along with some other common sense measures).

Hand hygiene is a critical infection control tool, and poor hand hygiene practices are often part of the problem in outbreaks. Figuring out how to improve hand hygiene is an important research area, albeit one in which few people are working.

A paper by Maureen and I, published recently in Epidemiology and Infection, looked at hand hygiene compliance in a petting zoo and how to improve it. The study involved using webcams to remotely and discretely observe hand hygiene practices in people attending a petting zoo. We've previously done observer-based studies, where you have someone standing there watching, but it's possible that this method falsely elevates results because some people might notice they're being watched and be more likely to wash their hands. It's also easier to record a lot of data and evaluate it over time (i.e. by watching it on video), than try to collect everything accurately in real time.

The published study involved a large petting zoo at the University of Guelph's annual open house. It's a well designed and operated event, which needs to be considered when evaluating the results, since petting zoos vary greatly in quality.

Overall hand hygiene compliance at this particular event was 58%. That means 58% of people that came into the petting zoo washed their hands or used a hand sanitizer on the way out. (It doesn't mean they all did it well, but they at least they did something). In some ways, that number's good, when you compare to our earlier petting zoo observation study, (or even to results of hand hygiene rates of physicians in some hospitals). However, for such a short-term activity where there is easy access to facilities to wash hands or use a hand sanitizer, there's much room for improvement.

During the petting zoo, a few thing were changed at defined times to see if they would improve hand hygiene rates. Two things resulted in increased hand hygiene compliance; a combination of petting zoo personnel actively offering visitors hand sanitizer near the exit and improving hand hygiene signs, and having personnel walking through the zoo reminding people to wash their hands. This suggests that people need an active reminder to clean or sanitize their hands. Whether they don't think about it, or can't be bothered unless someone points it out, is unclear, but having personnel encouraging hand hygiene is something to consider to help improve infection control. It's practical for short-term events like petting zoos at fairs and similar exhibits, although perhaps not as practical for permanent exhibits.

People who entered pens or touched animals were more likely to wash their hands than people who didn't. This is presumably because people who had contact with animals were more likely to recognize a risk. However, while people who touch animals are presumably at higher risk, simply being in the area is enough to pick up an infection. In some outbreaks, people who went into the petting zoo but never touched an animal got sick. That's why there is a need to remind people that everyone must wash their hands after leaving a petting zoo, not just those who actually petted the animals.

A few other concerns were noted. Despite warnings on prominent signs, 10% of people carried food or drink into the petting zoo area. This probably increases disease transmission risks since people may eat or drink before they wash their hands, or directly contaminate their food or drink while in the petting zoo area.

Overall, hand hygiene rates weren't bad (and were better than I was expecting), but there is still room for improvement. Considering how quick, easy and cheap it is, there's no reason not to strive for 100% compliance. 

Kennel cough vaccination and boarding

It's very common for kennels to require dogs be vaccinated against "kennel cough" before they are allowed in. There are two main reasons for this:

  1. Reducing the risk that a dog will bring kennel cough into the facility and spread it to other dogs.
  2. Reducing the likelihood that a dog will acquire kennel cough if someone else brought it in.

Overall, it's a sound policy, but it's far from 100% effective and it needs to be part of an overall kennel infection control program to work. Relying solely on vaccination to prevent kennel cough is a weak approach that can ultimately fail, particularly if other infection control practices are poor or if vaccination protocols are illogical.

Why isn't it 100% effective?

1) Kennel cough is a syndrome, not a specific disease. It can be caused by many different viruses and bacteria, often in combination. Kennel cough vaccines are typically targeted against Bordetella bronchiseptica +/- canine parainfluenza, two important causes of kennel cough, but not the only causes.

2) No vaccine is 100% effective. Vaccines help reduce the risk of illness, but they don't completely eliminate it. Some vaccines are better than others, and some animals respond better to vaccines than others.

3) Timing is another issue. One of the weak points of many kennel protocols is the requirement that the dog be vaccinated "before entry," or within a certain number of weeks or months. The problem with this is vaccines are not immediately effective. What often happens is people decide to board their animal at the last minute or realize the night before that they need their dog vaccinated, so the vaccine gets given a day (or less) before kenneling. The intranasal kennel cough vaccine (squirted up the nose) takes a few (3-5) days to be effective, and the injectable vaccine takes even longer (a week or more). Vaccination very soon before boarding, particularly for a dog that has never been vaccinated against kennel cough before, is unlikely to result in protection from infection by the time of boarding.

Requiring vaccination before boarding makes sense, but it's important to remember that:

  • It's not 100% effective.
  • It doesn't negate the need for a good infection control program.
  • It needs to be given at an appropriate time to be effective.